Transformer



y 1950 A. E. FEINBERG 2,509,137

- 'mnsr'omn Filed May 17, 1949 Patented May 23, 1950 TRANSFORMER Albert E. Feinberg, Chicago, 111., assignor to Advancc Transformer Co., Chicago, 111., a corporation of Illinois Application May 17, 1949, Serial No. 93,644

Claims.

This invention relates to electromagnetic induction devices, such as for example. transformers and chokes which utilize iron cores formed of laminations, and especially is directed to a device having a core which is provided with air gaps of relatively narrow extent, and a method of achieving such air gaps in a simple and easily executed manner.

In transformers and chokes used as parts of ballasts for initiating and maintaining the arc of gaseous discharge devices it is often necessary to utilize air gaps which are of the order of .005 to .020 inch in thickness. The production of laminations for such electromagnetic devices becomes expensive because of the tolerances which must be observed. This especially becomes true where laminations must be formed with as little waste as possible, and the punchings from a large member are used to produce a portion of a smaller core member to be associated with the larger member after winding.

My new invention has as its principal objects the provision of an extremely economical electromagnetic induction device having a laminated core in which at least one air gap is formed of a relatively small thickness; the provision of a novel method of producing such an induction device; the provision of a device of the character described in which the air gap thickness may be accurately achieved and maintained; and the provision of a device includin an outer shell member and a central winding member punched from the same blank forming the outer shell member without allowance for the provision of an air gap, but in which'device there is provided an accurate air gap.

Other objects will become apparent as the description proceeds.

For illustration a preferred embodiment has been described and is shown in the drawings in which Fig. 1 is a plan view of the shell member of the core of my device with the central winding leg removed.

Fig. 2 is a plan view of the winding leg alone having windings thereon.

Fig. 3 is a plan view of the shell and leg of Figs. 1 and 2 assembled together, but with no air gaps formed.

Fig. 4 is a view similar to that of Fig. 3 but showing the air gap forming pins in place to provide the narrow air gaps.

Fig. 5 is a sectional view taken through the device shown in Fig. 4 along the line 55 and in the indicated direction.

Fig. 6 is a fragmentary plan view of a modified form of the device utilizing rounded pin recesses prior to forcing the air gap forming pins into position.

Fig. 7 is a view similar to that of Fig. 6 but after the air gap forming pin is in position.

Referring now to the figures, I have designated my device generally by the reference character In. Same may be termed a transformer in the description, but merely for convenience, since I do not wish to be limited to transformers. There is provided a core formed of a frame-like shell 11 and a central winding leg l2 having coils l3 and I4 wound thereon, the assembled leg 12 as shown in Fig. 2 being associated with the shell 11 as shown in Figs. 3 and 4. v

The shell II consists of identical thin 1am inations stacked and held together in any suitable manner, such as for example by rivets or the like not shown herein. The shape of these laminations is as shown in the view of Fig. 1. Likewise the central winding leg I2 is formed of a stack of laminations. Referring now to the formation of the shell, same consists of end yokes l5 and I6 connected by the elongated side legs l1 and I8. The legs are provided with extensions 19 and 20 which face one another in the space between the legs and have their free ends spaced apart a distance equal to the precise width of the winding leg 12. Each of the extensions l9 and 20 is notched as shown at 2| and 22, said notches being triangular in formation. The yokes l5 and I6 are provided with notches 23 and 24 on their inner sides for centering the winding le 12 during assembly.

The winding leg I2 is formed having a width exactly the distance between the ends of the extensions 19 and 20 and with its ends pointed in the exact shape of the notches 23 and 24 as shown at 25 and 26. The length of the winding leg 12 is likewise precisely equal to the distance between the notches 23 and 24. Obviously, during the formation of the laminations making up the shell ll, there will be punched out or otherwise formed laminations corresponding in size and shape to the winding leg 12. The only waste will be formed in the spaces between the sides of the extensions 19 and 20 and the unnotched sides of the yokes l5 and 16. Such waste will comprise rectangular members, whereby when the leg 12 is assembled within the shell ll, there will be open coil spaces 21, 28, 29 and 30.

The center of the leg 12 is notched as shown at 3| and 32, said notches being of the same size and shape as the notches 2| and 22, and positioned to face the same, being of reverse formation, whereby when the shell 11 and leg 12 are assembled there will be formed substantially square recesses extendin completely through the stacked core of the transformer I 0 as shown at 33 and 34.

After the laminations forming the shell II and the central winding leg have been formed in any suitable manner the coils l3 and H are installed upon the body of the winding leg l2 between the notches 3| and 32 and the ends 25 and 25. The assembled winding leg I 2 is then laid over the stacked shell II and forced into the same resulting in the formation shown in Fig. 3. In this condition, the leg is tightly engaged because of the fact that the shape of the leg I2 is such as perfectly to mate with the notches 23 and 24, and the ends of the extensions l9 and 20. There is no spacing between the sides oi the leg l2 and the ends of the extensions l9 and 20, there being abutting joints indicated at 35 and 31.

It is desired to form air gaps of relatively narrow width at these joints 36 and 31. Heretoiore if such air gaps as contemplated by my invention, namely only a few thousandths of an inch in thickness, were contemplated, it would have been necessary to in some manner decrease the space between the ends of the extensions l9 and 20 during the formation thereof, or it would have been necessary to decrease the width of the laminations forming the leg [2. Thus, the leg laminations would not be capable of being directly stamped out of the same member forming the shell without additional operations being performed thereon, as can be done in using my new invention. This is achieved in the manner described below.

After the formation shown in Fig. 3 is obtained, preferably non-ferrous pins 38 and 33 are driven into the square recesses 33 and 34. The diameter of these pins is greater than the side dimension of the squared recesses 33 and 34, whereby the Joints 35 and 31 will be spread apart thereby forming the air gaps 40 and 4|. The side legs I! and I8 are sufficiently flexible to permit this, and the result is a tight fit which decreases noise and produces a firm and simple structure. The thickness of the air gaps to and 4| depends upon the diameter of the pins 40 and 4| so that a wide range of air gap thicknesses can be obtained without the necessity of complicated tools and dies, but merely by utilizing different diameter pins.

Although I have shown squared recesses 33 and 34, such recesses can be any suitable shape. For example, in Fig. 6 I have shown the leg 50 and extension having recesses not quite semi-circular in formation whereby when assembled there will be formed a substantially oval recess 52 in the joint 53. A round pin 54 will open the joint 53 to provide an air gap 55.

Various changes can be made without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent of the United States is:

1. In an electromagnetic device which includes a laminated core having a generall rectangular shell member with aligned central extensions, a winding leg disposed within the shell and having the ends of said extensions juxtaposed relative to opposite sides of said winding leg, means forming air gaps between the said ends and the respective sides of said winding leg, comprising mating half recesses extending completely through said core, each end and its juxtaposed side being provided with a half recess whereby together to form a whole recess, and a plug in whole recess maintaining spacing between each of said ends and its respective side of said leg.

2. in an eiectromagnet device which includes a laminomd core having an elongated portion and a core part having a free end normally engaged in abutting relationship against a side of the elongated portion in a closed joint, mating half recesses in said end and side forming thereby a recess extending through the core, a member disposed in the recess and having a cross section greater in extent than can be accommodated by said recess whereby the said joint is spread a predetermined amount to provide an air gap.

3. In an electromagnetic device which includes a laminated core having an elongated portion and a core part having a free end normally engaged in abutting relationship against a side of the elongated portion in a closed joint, making half recesses in said end and side forming thereby a recess extending through the core, a member disposed in the recess and having a cross section greater in extent than can be accommodated by said recess whereby the said joint is spread a predetermined amount to provide an air gap, said device having a frame-like shell, and said core part comprising an integral extension on the inside of the shell, and said elongated portion comprising a central winding leg disposed in the shell.

4. In an electromagnetic device which includes a laminated core having an elongated portion and a core part having a free end normally engaged in abutting relationship against a side of the elongated portion in a closed joint, mating half recesses in said end and side forming thereby a recess extending through the core, a member disposed in the recess and having a cross section greater in extent than can be accommodated by said recess whereby the said joint is spread a predetermined amount to provide an air gap, there being a second core part on the side of said elongated portion opposite to the first mentioned port, normally abutting thereagainst and having half recesses like the first mentioned and a second member forming an air gap therebetween.

5. In an electromagnet device of the character described, a frame-like laminated shell having a yoke at opposite ends connected by means of side legs, a central winding leg engaged within the shell, having its ends abutting against the inside edges of said yokes and having windings provided thereon, said windings being spaced apart providing a portion of said leg not covered thereby, said side legs having inwardly directed extensions aligned with said uncovered portion of said central winding leg and with the ends of such extension abutting against opposite sides of said winding leg in a normally closed joint, there being recesses on each joint extending through said extensions and winding leg with portions of each recess provided on each side of each joint, 2. member disposed in each of said recesses of a size to expand said joint when said members are in position whereby to form air gaps of said expanded joints.

.i lllBERT E. FEINBER-G.

EILEFERENCES CITED The following references are of record in the file of this patent:

UNETED STATES PATENTS Number Name Date 1,297,161 I-l'endric'xs Mar. 11, 1919 1,606,755 Field Nov. 16, 1926 1,685,064 Wagner July 5, 1927 2,382,638 Kaiser Aug. 14, 1945 2388,7622 Scliwennesen a Nov. 22,, 1949 

